Papers by Keyword: Mechanical Performance

Abstract: Among all additive manufacturing techniques, fused deposition modeling (FDM) has been used the most extensively to fabricate continuous fiber reinforced polymers. Onyx, a short carbon fiber reinforced PA6 composite material developed by Markforged, has received widespread attention, and been employed as matrix in FDM-fabricated composites. This study investigates the tensile properties of continuous glass fiber (GF) reinforced Onyx (CGFRO) composites under quasi-static loading. CGFRO contains three different components, which are short carbon fiber in micrometer scale, continuous glass fiber and polyamide-d thermoplastic. The synergistic reinforcing behavior of these three components was evaluated experimentally by testing Onyx material, and CGFRO with different volume fractions of fibers (Vf). It was found that the failure mode of Onyx was different from that of GF/Onyx and the deformation modes of GF/Onyx varied with the volume fraction of glass fiber. The tensile properties of CGFRO increased with glass fiber volume fractions, where 42% Vf specimens exhibited the highest tensile modulus and strength of 10 GPa and 383 MPa, respectively, which are approximately nine times higher than that of Onyx parent material.

Abstract: The mechanical and durability properties were best at 45% GGBS and 5% Waste Glass with 0.4 water/cement ratio. The recycled materials implemented for mix proportion were waste glass provided considerably to enhance its properties when added with GGBS. In most of the research work, the effect of WG and GGBS in concrete as a partial substitution of fine aggregate and cement individually is analyzed. Previous studies only show the individual impact of these concrete recycled materials on mechanical and durability properties. In the present study, an exact optimum substitution level of cement by GGBS (15 – 60% at an increment of 15%) and fine aggregate by the waste glass (5 – 20% at an increase of 5%) combined for OPC concrete mix. Mechanical (compressive strength, split tensile strength and flexural strength) and microstructural properties (FESEM) were observed on the combination of waste glass and GGBS concrete mix.

Abstract: Preparation, microstructure and mechanical performance of novel supplementary cementing materials prepared with electroplating sludge and steel slag as raw materials were studied. It was found that the electroplating sludge could be mixed with steel slag at appropriate ratios to make SCMs that posse certain compressive strength. The results shows that the supplementary cementing materials prepared in this article can increase the compressive strengths of cement when it substitutes for cement in appropriate proportion. The microstructure and hydration products of cement with SCMs were examined by XRD and SEM. The results indicated that the content of calcium hydroxide formed in paste significantly reduced and Aft increased, as the content of the supplementary cementing materials increased. In addition, the heavy metals elements in the electroplating sludge could be effective cured in cement pastes and reduced the pollution to the environment.

Abstract: In this article, the supercritical carbon dioxide (Sc-CO₂) was used as a medium for hot-drawing of F-III fibers. The conditions of hot-drawing were selected to be the temperature of 250 °C, pressure of 14 MPa, time of 60 min, and different tensions, which were 0, 3, 4.5, 6, and 7.5 g·d^-1, respectively. All samples including the untreated and treated F-III fibers were characterized by a mechanical tester and X-ray diffraction (XRD). Results showed that the Sc-CO₂ and applied tension could both promote the crystallinity and degree of orientation of F-III fibers at a temperature below the Tg of F-III fibers in Sc-CO₂. Moreover, compared with the untreated, the tensile strength and modulus of treated F-III fibers tended to increase with the increase of tension in the range of 0 ~ 6 g·d^-1. In summary, this provided a new treatment mode for the hot-drawing of fibers.

Abstract: Oxygen is considered to be an impurity in titanium and its alloys, and it enhances their brittleness. However, oxygen has also been recognized as a useful ingredient to improve the mechanical performance of titanium alloys for biomedical applications, because oxygen is a lightweight interstitial element that is non-toxic and non-allergenic. Some reports show that adding oxygen improves both the strength and the ductility of titanium alloys for biomedical applications. The effects of oxygen addition on the mechanical performance of titanium alloys for biomedical aplications are described.

Abstract: Unique and desirable properties of composites, converted them to one of the favorablematerials in a wide range of applications. At present, various composites are utilized in aircraftinterior such as overhead bins, side walls, ceiling and bulkheads. Since adhesively bondedcomposite joints play crucial role in performance of various engineering components,manufacturing of the joints is an important issue. In the present work, an overview of compositesandwich joints is presented, and different types of defects on this component are outlined. Later,some techniques for detection of defects in the sandwich-structured composites are mentioned.Moreover, as a case study, strength and fracture of sandwich T-joints with and withoutmanufacturing defects are compared. The case study proved the role of manufacturing defects inunfavorable performance of the joints. Results of the case study indicated that it is necessary to usedifferent advanced techniques to investigate and assess performance of sandwich joints prior totheir utilization. Concerning to high applications of sandwich composite joints and limitations ofnondestructive tests, there is still a potential to provide a method or a technique which wouldestimate performance of the joints under different loading conditions.

Abstract: A novel multi-phase carboxylate (MPC) salt was prepared by free radical polymerization. Influence of MPC salt on properties of mortar under sulfate environment was investigated. The results from static solution soaking and wet-dry cycling tests indicated that MPC would not bring negative effects on strength and shrinkage of mortar. In particular, MPC was able to reduce the strength loss as a result of inhibiting the generation and growth of ettringite in static solution soaking test. The crystal expansion of AFt was reduced since the Ca²⁺ dissolution and SO₄^2- ingress were less. Meanwhile, the strength loss of mortar under sulfate wet-dry cycling could be reduced as well by MPC. MPC inhibited the growth of CaSO₄·2H₂O crystals by replacing the functional groups. The growth of micro-cracks in cement paste was inhibted and the the risk of crystal expansion and destruction of mortar was reduced. It was believed that MPC exhibited an excellent sulfate attack resistance for mortar.

Abstract: In order to study the influence of different types of weld defects, such as slag inclusion, porosity, incomplete fusion, incomplete fusion, burn through, crack on the mechanical performance of X65 marine pipe welding joint (Φ323.9 x 16 mm), the test on the mechanical properties of static tensile, fracture toughness CTOD and fatigue life were carried out to achieve the maximal defect tolerance size allowed in this paper. Research shows that the existence of crack defects would significantly reduce the fracture strength and the fatigue life of welded joint, the application of the maximal defect tolerance size allowed based on crack defects assessment can provide referential basis for the safe and stable operation of marine pipelines.

Abstract: FRP (fiber reinforced polymer material) having a high specific strength and specific modulus, good corrosion resistance and other advantages. FRP materials in civil engineering industry has been more and more popular, and gradually become a hot issue in the world. In order to take full advantage of a variety of materials and overcome the problems in the FRP structure, this paper mainly studies the composite structure of FRP and traditional materials, namely FRP-concrete composite beam structure. The mechanical parameters of FRP (mainly including CFRP and GFRP) were selected. And the stress -strain diagram of FRP materials are drawn. Through tensile tests on FRP (including CFRP and GFRP), FRP was found to belong to brittle materials. As well as the mechanical properties of FRP materials, the ultimate load analysis, the decision to use CFRP as a composite beam structural stiffness of the research materials. When considering concrete shrinkage, creep, temperature difference effect, the stiffness of composite beam meets the requirement. The deflection of FRP- concrete composite beam is verified by mechanical formula. The change of the concrete stiffness will affect the change of the structural stiffness of the FRP- concrete composite beam. As well as through an example, it is found that the concrete shrinkage and temperature can affect the change of the stiffness of the composite structure.

Abstract: Cold-formed steel (CFS) is steel based material that has been used broadly in construction and building as non-structural or structural element. Many researchers are studying the CFS as structural element, such as column, beam and roof truss. With a lot of advantages, CFS becoming more popular when distinguished by other material. CFS also owned the unstable and unsafe circumstances when the section in a slender or long column. The main issue that influenced the unstable circumstances for slender column is recognised as local, distortional and global buckling. As a result, the study of the mechanical performance of slender column must be investigated to get some important information for design and analysis intention. Three samples of CFS channel column with a height of 1000, 1500 and 2000 mm are determined. From the testing, the ultimate load of the slender CFS column decreases with increasing of the height of the column. All columns are illustrated having the global buckling when subjected to load. The flange and web deformation of the column is becoming not stiff when the height of the column is increased.